(function() {

    var global = window;
    /**
     * 模板引擎
     * 若第二个参数类型为 String 则执行 compile 方法, 否则执行 render 方法
     * @class HteOS.Template
     * @param   {String}            模板ID
     * @param   {Object, String}    数据或者模板字符串
     * @return  {String, Function}  渲染好的HTML字符串或者渲染方法
     */
    var template = global.template = function(id, content) {
        return template[
            typeof content === 'string' ? 'compile' : 'render'
            ].apply(template, arguments);
    };

    template.version = '2.0.4';
    template.openTag = '<%'; // 设置逻辑语法开始标签
    template.closeTag = '%>'; // 设置逻辑语法结束标签
    template.isEscape = true; // HTML字符编码输出开关
    template.isCompress = false; // 剔除渲染后HTML多余的空白开关
    template.parser = null; // 自定义语法插件接口

    /**
     * 渲染模板
     * @name    template.render
     * @param   {String}    模板ID
     * @param   {Object}    数据
     * @return  {String}    渲染好的HTML字符串
     */
    template.render = function(id, data) {

        var cache = template.get(id) || _debug({
            id: id,
            name: 'Render Error',
            message: 'No Template'
        });

        return cache(data);
    };

    /**
     * 编译模板
     * 2012-6-6 @TooBug: define 方法名改为 compile，与 Node Express 保持一致
     * @name    template.compile
     * @param   {String}    模板ID (可选，用作缓存索引)
     * @param   {String}    模板字符串
     * @return  {Function}  渲染方法
     */
    template.compile = function(id, source) {

        var params = arguments;
        var isDebug = params[2];
        var anonymous = 'anonymous';

        if(typeof source !== 'string') {
            isDebug = params[1];
            source = params[0];
            id = anonymous;
        }

        try {

            var Render = _compile(id, source, isDebug);

        } catch(e) {

            e.id = id || source;
            e.name = 'Syntax Error';

            return _debug(e);

        }

        function render(data) {

            try {

                return new Render(data, id) + '';

            } catch(e) {

                if(!isDebug) {
                    return template.compile(id, source, true)(data);
                }

                return _debug(e)();

            }

        }

        render.prototype = Render.prototype;
        render.toString = function() {
            return Render.toString();
        };

        if(id !== anonymous) {
            _cache[id] = render;
        }

        return render;

    };

    var _cache = template.cache = {};

    // 辅助方法集合
    var _helpers = template.helpers = (function() {

        var toString = function(value, type) {

            if(typeof value !== 'string') {

                type = typeof value;
                if(type === 'number') {
                    value += '';
                } else if(type === 'function') {
                    value = toString(value.call(value));
                } else {
                    value = '';
                }
            }

            return value;

        };

        var escapeMap = {
            "<": "&#60;",
            ">": "&#62;",
            '"': "&#34;",
            "'": "&#39;",
            "&": "&#38;"
        };

        var escapeHTML = function(content) {
            return toString(content)
                .replace(/&(?![\w#]+;)|[<>"']/g, function(s) {
                    return escapeMap[s];
                });
        };

        var isArray = Array.isArray || function(obj) {
            return({}).toString.call(obj) === '[object Array]';
        };

        var each = function(data, callback) {
            if(isArray(data)) {
                for(var i = 0, len = data.length; i < len; i++) {
                    callback.call(data, data[i], i, data);
                }
            } else {
                for(i in data) {
                    callback.call(data, data[i], i);
                }
            }
        };

        return {

            $include: template.render,

            $string: toString,

            $escape: escapeHTML,

            $each: each

        };
    })();

    /**
     * 添加模板辅助方法
     * @name    template.helper
     * @param   {String}    名称
     * @param   {Function}  方法
     */
    template.helper = function(name, helper) {
        _helpers[name] = helper;
    };

    /**
     * 模板错误事件
     * @name    template.onerror
     * @event
     */
    template.onerror = function(e) {
        var message = 'Template Error\n\n';
        for(var name in e) {
            message += '<' + name + '>\n' + e[name] + '\n\n';
        }

        if(global.console) {
            console.error(message);
        }
    };

    // 获取模板缓存
    template.get = function(id) {

        var cache;

        if(_cache.hasOwnProperty(id)) {
            cache = _cache[id];
        } else if('document' in global) {
            var elem = document.getElementById(id);

            if(elem) {
                var source = elem.value || elem.innerHTML;
                cache = template.compile(id, source.replace(/^\s*|\s*$/g, ''));
            }
        }

        return cache;
    };

    // 模板调试器
    var _debug = function(e) {

        template.onerror(e);

        return function() {
            return '{Template Error}';
        };
    };

    // 模板编译器
    var _compile = (function() {

        // 数组迭代
        var forEach = _helpers.$each;

        // 静态分析模板变量
        var KEYWORDS =
            // 关键字
            'break,case,catch,continue,debugger,default,delete,do,else,false' +
            ',finally,for,function,if,in,instanceof,new,null,return,switch,this' +
            ',throw,true,try,typeof,var,void,while,with'

            // 保留字
            +',abstract,boolean,byte,char,class,const,double,enum,export,extends' +
            ',final,float,goto,implements,import,int,interface,long,native' +
            ',package,private,protected,public,short,static,super,synchronized' +
            ',throws,transient,volatile'

            // ECMA 5 - use strict
            +
            ',arguments,let,yield'

            +
            ',undefined';

        var REMOVE_RE = /\/\*[\w\W]*?\*\/|\/\/[^\n]*\n|\/\/[^\n]*$|"(?:[^"\\]|\\[\w\W])*"|'(?:[^'\\]|\\[\w\W])*'|[\s\t\n]*\.[\s\t\n]*[$\w\.]+/g;
        var SPLIT_RE = /[^\w$]+/g;
        var KEYWORDS_RE = new RegExp(["\\b" + KEYWORDS.replace(/,/g, '\\b|\\b') + "\\b"].join('|'), 'g');
        var NUMBER_RE = /^\d[^,]*|,\d[^,]*/g;
        var BOUNDARY_RE = /^,+|,+$/g;

        var getVariable = function(code) {
            return code
                .replace(REMOVE_RE, '')
                .replace(SPLIT_RE, ',')
                .replace(KEYWORDS_RE, '')
                .replace(NUMBER_RE, '')
                .replace(BOUNDARY_RE, '')
                .split(/^$|,+/);
        };

        return function(id, source, isDebug) {

            var openTag = template.openTag;
            var closeTag = template.closeTag;
            var parser = template.parser;

            var code = source;
            var tempCode = '';
            var line = 1;
            var uniq = {
                $data: 1,
                $id: 1,
                $helpers: 1,
                $out: 1,
                $line: 1
            };
            var prototype = {};

            var variables = "var $helpers=this," +
                (isDebug ? "$line=0," : "");

            var isNewEngine = ''.trim; // '__proto__' in {}
            var replaces = isNewEngine ?
                ["$out='';", "$out+=", ";", "$out"] :
                ["$out=[];", "$out.push(", ");", "$out.join('')"];

            var concat = isNewEngine ?
                "$out+=$text;return $text;" :
                "$out.push($text);";

            var print = "function($text){" + concat + "}";

            var include = "function(id,data){" +
                "data=data||$data;" +
                "var $text=$helpers.$include(id,data,$id);" +
                concat +
                "}";

            // html与逻辑语法分离
            forEach(code.split(openTag), function(code) {
                code = code.split(closeTag);

                var $0 = code[0];
                var $1 = code[1];

                // code: [html]
                if(code.length === 1) {

                    tempCode += html($0);

                    // code: [logic, html]
                } else {

                    tempCode += logic($0);

                    if($1) {
                        tempCode += html($1);
                    }
                }

            });

            code = tempCode;

            // 调试语句
            if(isDebug) {
                code = "try{" + code + "}catch(e){" +
                    "throw {" +
                    "id:$id," +
                    "name:'Render Error'," +
                    "message:e.message," +
                    "line:$line," +
                    "source:" + stringify(source) +
                    ".split(/\\n/)[$line-1].replace(/^[\\s\\t]+/,'')" +
                    "};" +
                    "}";
            }

            code = variables + replaces[0] + code +
                "return new String(" + replaces[3] + ");";

            try {

                var Render = new Function("$data", "$id", code);
                Render.prototype = prototype;

                return Render;

            } catch(e) {
                e.temp = "function anonymous($data,$id) {" + code + "}";
                throw e;
            }

            // 处理 HTML 语句
            function html(code) {

                // 记录行号
                line += code.split(/\n/).length - 1;

                // 压缩多余空白与注释
                if(template.isCompress) {
                    code = code
                        .replace(/[\n\r\t\s]+/g, ' ')
                        .replace(/<!--.*?-->/g, '');
                }

                if(code) {
                    code = replaces[1] + stringify(code) + replaces[2] + "\n";
                }

                return code;
            }

            // 处理逻辑语句
            function logic(code) {

                var thisLine = line;

                if(parser) {

                    // 语法转换插件钩子
                    code = parser(code);

                } else if(isDebug) {

                    // 记录行号
                    code = code.replace(/\n/g, function() {
                        line++;
                        return "$line=" + line + ";";
                    });

                }

                // 输出语句. 转义: <%=value%> 不转义:<%=#value%>
                // <%=#value%> 等同 v2.0.3 之前的 <%==value%>
                if(code.indexOf('=') === 0) {

                    var isEscape = !/^=[=#]/.test(code);

                    code = code.replace(/^=[=#]?|[\s;]*$/g, '');

                    if(isEscape && template.isEscape) {

                        // 转义处理，但排除辅助方法
                        var name = code.replace(/\s*\([^\)]+\)/, '');
                        if(!_helpers.hasOwnProperty(name) &&
                            !/^(include|print)$/.test(name)
                        ) {
                            code = "$escape(" + code + ")";
                        }

                    } else {
                        code = "$string(" + code + ")";
                    }

                    code = replaces[1] + code + replaces[2];

                }

                if(isDebug) {
                    code = "$line=" + thisLine + ";" + code;
                }

                getKey(code);

                return code + "\n";
            }

            // 提取模板中的变量名
            function getKey(code) {

                code = getVariable(code);

                // 分词
                forEach(code, function(name) {

                    // 除重
                    // TODO: name 可能在低版本的安卓浏览器中为空值，这里后续需要改进 getVariable 方法
                    // @see https://github.com/aui/artTemplate/issues/41#issuecomment-29985469
                    if(name && !uniq.hasOwnProperty(name)) {
                        setValue(name);
                        uniq[name] = true;
                    }

                });

            }

            // 声明模板变量
            // 赋值优先级:
            // 内置特权方法(include, print) > 私有模板辅助方法 > 数据 > 公用模板辅助方法
            function setValue(name) {

                var value;

                if(name === 'print') {

                    value = print;

                } else if(name === 'include') {

                    prototype["$include"] = _helpers['$include'];
                    value = include;

                } else {

                    value = "$data." + name;

                    if(_helpers.hasOwnProperty(name)) {

                        prototype[name] = _helpers[name];

                        if(name.indexOf('$') === 0) {
                            value = "$helpers." + name;
                        } else {
                            value = value +
                                "===undefined?$helpers." + name + ":" + value;
                        }
                    }

                }

                variables += name + "=" + value + ",";
            }

            // 字符串转义
            function stringify(code) {
                return "'" + code
                // 单引号与反斜杠转义
                    .replace(/('|\\)/g, '\\$1')
                    // 换行符转义(windows + linux)
                    .replace(/\r/g, '\\r')
                    .replace(/\n/g, '\\n') + "'";
            }

        };
    })();
})();